using System; using System.Collections.Generic; using System.IO; using System.Linq; using System.Numerics; using System.Text; namespace ProgrammingContestTemplateByDotNetCore { #region "Input and Output Classes" class Scanner : IDisposable { private readonly Queue _buffer; private readonly char[] _sep; private readonly TextReader _reader; public Scanner(TextReader reader = null, char[] sep = null) { _buffer = new Queue(); _sep = sep ?? new[] { ' ' }; _reader = reader ?? Console.In; } public Scanner(string path, char[] sep = null) : this(new StreamReader(path), sep) { } private void CheckBuffer() { if (_buffer.Any() || _reader.Peek() == -1) return; string str = string.Empty; for (; string.IsNullOrWhiteSpace(str); str = _reader.ReadLine()) { } var values = str.Split(_sep).Where(s => !string.IsNullOrWhiteSpace(s)); foreach (var item in values) { _buffer.Enqueue(item); } } public string Next() { CheckBuffer(); return _buffer.Dequeue(); } public string[] GetStringArray(int count) => Enumerable.Range(0, count) .Select(e => Next()) .ToArray(); public int NextInt() => int.Parse(Next()); public int[] GetIntArray(int count) => Enumerable.Range(0, count) .Select(e => NextInt()) .ToArray(); public long NextLong() => long.Parse(Next()); public long[] GetLongArray(int count) => Enumerable.Range(0, count) .Select(e => NextLong()) .ToArray(); public double NextDouble() => double.Parse(Next()); public double[] GetDoubleArray(int count) => Enumerable.Range(0, count) .Select(e => NextDouble()) .ToArray(); public decimal NextDecimal() => decimal.Parse(Next()); public decimal[] GetDecimalArray(int count) => Enumerable.Range(0, count) .Select(e => NextDecimal()) .ToArray(); public BigInteger NextBigInt() => BigInteger.Parse(Next()); public BigInteger[] GetBigIntArray(int count) => Enumerable.Range(0, count) .Select(e => NextBigInt()) .ToArray(); public bool IsEnd { get { CheckBuffer(); return !_buffer.Any(); } } public void Dispose() { if (!_reader.Equals(Console.In)) _reader.Dispose(); } } class Writer : IDisposable { private readonly TextWriter _writer; private readonly StringBuilder _cache; private readonly bool _isReactive; public Writer(TextWriter writer = null, bool isReactive = false) { _writer = writer ?? Console.Out; _isReactive = isReactive; if (!_isReactive) _cache = new StringBuilder(); } public Writer(string path) : this(new StreamWriter(path)) { } public Writer(bool isReactive) : this(null, isReactive) { } public void Write(object value) { if (_isReactive) { _writer.Write(value); _writer.Flush(); } else { _cache.Append(value); } } public void WriteFormat(string format, params object[] values) { var value = string.Format(format, values); Write(value); } public void WriteLine(object value = null) { Write($"{value}{Environment.NewLine}"); } public void WriteLine(string format, params object[] values) { WriteFormat($"{format}{Environment.NewLine}", values); } public void Dispose() { if (!_isReactive) { _writer.Write(_cache); _writer.Flush(); } if (!_writer.Equals(Console.Out)) { _writer.Dispose(); } } } #endregion class MainClass : IDisposable { #region "Template" /// 入力を受け取る private readonly Scanner sc; /// 出力を行う private readonly Writer wr; private const string _inputFile = "input.txt"; private const string _outFile = "output.txt"; static void Main(string[] args) { using (new MainClass()) { } } public MainClass() { wr = new Writer(_isReactive); // TODO: ファイルに出力したい場合はこっち → wr = new Writer(_outFile); #if DEBUG // 手元では、ファイルから入力を受け取る sc = new Scanner(_inputFile); #else // 提出時、標準入力から受け取る sc = new Scanner(); #endif Solve(); } public void Dispose() { sc?.Dispose(); wr?.Dispose(); } #endregion void Solve() { var N = sc.NextInt(); var S = sc.Next(); int ans = S.Count(c => c != '1' && c != '9'); S = string.Concat(S.Where(c => c == '1' || c == '9')); int one = 0, nine = 0; for (int i = 0; i < S.Length; i++) { if (S[i] == '1') { one++; } else { if (one > 0) { one--; ans++; } else { nine++; } } } int tmp = Math.Min(nine / 2, one); ans += tmp; one -= tmp; ans += one / 2; wr.WriteLine(ans); } /// /// TODO: リアクティブ問題か否かを指定してね♪ /// private const bool _isReactive = false; } }